Check valve with internal mass for progressive cavity pumps

ABSTRACT

The present invention corresponds to a check valve with an inertial mass that is installed in the bottom of the production tubing and above the progressive cavity pump (PCP) of an oil well, which prevents that the hydrostatic column that is inside of the production tubing go down in the moment where the artificial lift of the column stops for the detention of the PCP pump. If we prevent that this phenomenon to happen, the PCP pump will not rotate in the opposite direction of its normal operation and it will not be clogged by any particulate material that is contained in it.

FIELD OF THE INVENTION

The present invention is related to the field of mechanical engineeringand is applied in the hydrocarbon sector.

Specifically, the present invention it is applied in oil wells where thePCP pumps are used.

BACKGROUND OF THE INVENTION

The patent request number 2006027513 “Improvement System in a fuel pump”has a fuel supply system that includes a fuel pump, a controller, andpulse circuit. The fuel pump has an electric motor that includes aconfigured winding that operates with a maximum efficacy for a firsttension to an expected load. The controller includes a pulse widthmodulator that generates an electrical signal that activates theelectrical motor. In normal operating conditions, the circuit acts as animpulse step and generates the excitation signal that is modulated atthe first voltage, to control the output of the pump. However, when abigger load than the expected is applied to the electric motor, thepulse circuit acts to scale the excitation signal to a second tensionthat is bigger than the first tension. The second tension drives theelectric motor to a tension beyond the maximum efficiency, but generallyprovides greater efficiency of the system

On the other hand, the patent application entitled Linear Pump withattenuation of escape pulsations, number 20060034709, describes a linearpump that has an axially aligned cylinder and a piston arrangementdriven by an electromagnet motor that has an escape camera that definesa cavity covered by a diaphragm. The diaphragm can be moved into thecavity in response to pressure fluctuations in the escape camera toreduce the pulsations in an air flow that goes out of the escape camera.A diaphragm is mounted over the cavity hollowed by a support ring thathas an open center allowing air acts against the diaphragm.

The previously mentioned patents do not achieve an effectiveoptimization for the pumping pumps because the pumps arose fromprogressive cavities.

Progressive Cavity Pumps (PCP) are machines that spin clockwise in orderto lift the oil from the bottom of the well to the surface. For this, isused a machine that is in the surface and that have a motor and a speedreducer, this machine is responsible for providing the necessaryrotation and power to move this pump. It also uses a string of rods,which connect the PCP pump rotor with the surface. The measure of thisrods are approximately 6 meters, but the drill string, which is theunion of various if these (dipsticks), can measure between 300 m to 3000m; these dipsticks transmit the power and rotation of the machine fromthe surface to the pump. The current problem is that when the PCP pumpstops, the hydrostatic column that is above it makes the PCP pump rotatein the opposite direction of its normal operation. In some cases, thisproduced the obstruction of the pump by particulate matter mixed withpetroleum extraction, such as sand. This also represents an estimatedtime delay between one and two hours, because it is impossible to startthe PCP pump while it is rotating in the opposite direction of itsoperation. This unjustified strike represents millions in losses to theindustry.

The Colombian patent “Check valve for progressive cavities pumps (PCP)”describes a 1 check valve for a progressive cavity pump (PCP) that seeksto optimize the operation of the PCP but it has not made an effectiveopposition to the hydrostatic column and it is susceptible ofimprovement.

In the petroleum production the progressive cavities pumps are normallyused and the need to prevent the reverse rotation of this machinespersists.

The effective solution of this technical problem could reduce theoperative costs of this artificial lift system.

Present invention is developed based on the first valve design thatprevents the reverse rotation of the progressive cavity pumps, whichwith the pertinent adjustments is going to optimize its performance.

DESCRIPTION OF INVENTION

The present invention provides a check valve with an inertial mass whichis installed at the bottom of the production tubing and above the PCPpump of the oil well, which prevents that the hydrostatic column that isinside the production tubing descend at the moment where the artificiallift is suspended as a result of stopping the PCP pump. At avoiding thatthis phenomenon appears we obtain that PCP pump do not turn in theopposed direction of its normal function, and that the same one is notclogged because of the particulate matter mixed with petroleumextraction, such as sand that it will be on it.

The check valve with an inertial mass for progressing cavity pumps isconstituted by eight components which are: a superior locknut, a stem, apiston, a cover piston, a niple, an inferior lock nut, an inner andouter packing. The piston moves axially through the stem and sits on theniple where it makes the hydraulic seal. When the piston is not seated,it allows the artificial lift of the fluid, and due to its geometrycharacteristics it's embedded in the superior lock nut which is coupledin the superior left screw of the stem, with the purpose of make ajointly rotation to the stem. The fact that this check valve forprogressive cavity pumps has an inertial mass, refers to the weight thatthe piston has. The piston's weight improves its descending movement,which guarantee the closing action of the check valve with an inertialmass for progressive cavity pumps.

The check valve with an inertial mass consists of eight main parts: anupper nut 1, an stem 2, a piston 3, a cover piston 4, a niple 5, a lowernut 6, an inner packing 17 and an outer packing 18, as the FIG. 1 showsThanks to the machining procedures, the stem 2 comprises a medium alloysteel shaft that at the ends has the 8 and 11 threads, besides the 9 and10 threads, as shown in FIG. 3. The upper left-hand thread 9 is locatednext the upper thread 8 while the lower left-hand thread 10 is locatednext to the bottom of the 11 thread. The upper thread 8 connects acuplin that belongs to the string of rods which is connected to a motorwith a speed reducer that is situated on the surface of the well.Through a cuplin, the lower thread 11 is connected to a rod string whichis connected to the PCP's rotor pump. In the lower left-hand thread 10the lock nut 6 is installed, in order to support the cuplin that settleson the thread 11 bottom. The piston 3 comprises an inner groove 13 whereis installed the internal packing 17 that retains the fluids between thepiston 3 and the stem 2, which can be seen in FIG. 4. It also has a step14 where the external packing 18 is installed and retains the fluidsbetween the niple 5 and piston 3, as the FIG. 4 shows. The piston 3 alsohas a thread 15 in which this part is cover by a cover piston 4, inorder to hold and ensure the position of the external packing 18. Thecover piston 4 has two parallel flat faces, as the FIG. 5 shows, whichserve as a support tool that is used for threading piston cover 4 in thethread 15 of the piston 3. The stem 2 is inserted through the piston 3and is restricted by the installation of the top lock nut 1 in the upperleft thread 8. The top lock nut 1 is characterized by two wedges 7, asshown in FIG. 2, which coupled the grooves for wedges 12 of the piston3. The niple 5 is installed in the pipe below the piston 3 and above thelower lock nut 6. This nipple 5 has a conical seat 16, as the FIG. 6shows, where the piston 3 is supported when the check valve with aninertial mass is closed.

The piston design contemplates the enough weight, to achieve descend andovercome the friction that occurs between the inner packing 17 and thestem 2. This ensures that the piston 3 that is inserted into the niple 5and seal the internal and the external passage of fluids, as the FIG. 8shows. Additionally, the design of the piston 3 includes the diameter 1(D1) and the diameter 2 (D2), as the FIG. 4 shows. The diameter D1 hasenough measure so the stem 2 can traverse the piston 3, with a slidingfit. In order to provide a fit loose between the stem 2 rod and thepiston 3, the D2 diameter is larger than the diameter D1. With all this,even if the stem 2 has a slight bucking, the system will ensures itsoperation.

When the well is producing, the piston 3 is lift to make a contact withthe upper lock nut 1 where it engages with the wedges 7 of the upper nut1, as the FIG. 8 shows. When the PCP stops rotating, the piston weightadded to the drag action of the fluid belonging to the hydrostaticcolumn, will make descend piston 3 to endure it in the conical seat 16,as the FIG. 9 shows. In this way, the outer packing 18 makes a sealbetween the piston 3 and the nipple 5.

DESCRIPTION OF THE FIGURES

FIG. 1: View of the check valve with an inertial mass for progressivecavity pumps assembled with their respective parts.

FIG. 2: Top nut 1 view.

FIG. 3: Stem 2 view.

FIG. 4: Piston 3 view.

FIG. 5: Top piston 4 view.

FIG. 6: Niple 5 view.

FIG. 7: Lower locknut 6 view.

FIG. 8: Perspective view of the check valve with an inertial mass forprogressive cavity pumps that is in an open position with the piston 3embedded in the wedges 7 of the upper nut 1.

FIG. 9: Perspective view of the check valve with an inertial mass forprogressive cavity pumps, in a closed position where the piston 3 isseated on the conical seat 16 o the niple 5.

LIST OF REFERENCE

1. Top Locknut

2. Stem

3. Piston

4. Cover piston

5. Niple

6. Lower Locknut

7. Chocks

8. Upper thread

9. Upper left thread

10. Lower left thread

11. Lower thread

12. Groove wedges

13. Inside groove

14. Step

15. Thread

16. Conical Seat

17. Internal packing

18. External packing

1. A check valve with an inertial mass for progressive cavity pump(PCP), characterized by having a piston 3 that overcomes the frictionalforce between the inner packing 17 and the stem 2 by mass, it makes adownward movement, and it makes a seal with niple 5 and closes the fluidpassage between the stem 2 and the niple
 5. 2. The check valve with aninertial mass for progressive cavity pump (PCP) of claim 1,characterized by having an upper nut 1, which presents the wedges 7 thatserve to fit the grooves wedge 12 of the piston 3, once its unseated ofthe niple 5 and the well is in production.
 3. The check valve with aninertial mass for progressive cavity pump (PCP) of claim 1, that ischaracterized by comprising a piston 3 that has a inter geometry with aninner diameter D1 that is lower than the diameter D2, which suspends theseizing of the piston 3 in the stem 2 by buckling of the stem
 2. 4. Thecheck valve with an inertial mass for progressive cavity pump (PCP) ofclaim 1, characterized by having a piston 3 that has an outer packing 18which is adjusted by the piston cover 4.